Primary progressive apraxia of speech (PPAoS) is a neurodegenerative syndrome characterized by speech apraxia at its onset; as it progresses, it often evolves into total mutism. Even though this syndrome is increasingly recognized, its early differential diagnostic is still complex. The objective of this study was to illustrate why a fine evaluation of speech and language is essential for the differential diagnosis of PPAoS. This longitudinal case study presents the progression of a PPAoS patient over a period of 5 years. Periodic neurological and speech-language assessments were carried out to follow the progression of neurological, memory, language and speech symptoms. The different diagnostic labels established over time were also reported. The evolution of the patient’s communication profile was characterized by a preservation of language components and episodic memory, in parallel with a progressive deterioration of speech which gradually reduced intelligibility, and was associated with signs of spasticity, resulting in a complete anarthria. This case study sheds light upon the evolution of a patient with PPAoS. A better understanding of the clinical profile and progression of PPAoS is necessary in order to improve early diagnosis and adequate care for these patients.